1) Stick to the facts. If he asks an actual question, or makes a blatant accusation, answer it as briefly and factually as possible. Examples:
- No, I do not want our children to fail. DS9 has made a lot of progress in his reading this year, he just needs time. He is currently doing X,Y,Z to improve his reading skills. He should be at grade level when he starts the charter school next fall.
- I have always encouraged the older boys to stay in contact with you. However, YOU are the adult here, and it should be YOU that is calling them and making the effort to reach out to them.


Don't get pulled into any name calling, blaming etc but do succinctly defend yourself against any attacks that need addressing. That way you can have it documented that you kept him informed, and document some fo the things like him not calling the boys.